Prevention of rust



Patented Dec. 12. i9-

' UNITED asaa'sos 2533,30 ICE PREVENTION OF RUST Franklin M. Watkins, Flossmoor, Ill., assignor to Sinclair ,Reflning Company, New York, N. Y., a corporation of Maine No lib-owing.s

4 Claims.

1 My invention is concerned with the maintenance of product pipe lines and storage vessels and more particularly pertains to a method ror preventing internal corrosion of equipment of this type when constructed of steel or other ironcontaining metal. The invention is especially valuable as applied to gasoline pipe lines but is also applicable to pipe lines employed in the transportation of other petroleum oil distillates as kerosene or fuel oil, for example.

Internal corrosion of product pipe lines is undesirable, inter alia, because of the contamination of distillate with corrosion products and because the consequent restriction of the internal diameter of the pipe decreases the volume of distillate which can be transported therethrough over a given period under a constant pressure.

I have made the surprising discovery that thelncorporation in light petroleum distillates of minute amounts of mahogany sulfonic acids or sulfonates materially retards internal corrosion and scale formation in pipe lines used for the transportation of such distillates. By minute amoun I refer to concentrations of the order of 1 to 100 parts per million.

Because of the presence of both free oxygen and water in gasoline as normally produced, pipe Application October 9, 1947, erial No. 778,753

lines employed in transporting gasoline are parl ticularly prone to corrode. During treating operations or storage it is not uncommon for as much as 006% of oxygen to become dissolved in gasoline. Water, picked up as troma washing operation, may be present as entrained water or as dissolved water. In any event, it is normally present in such amounts that the inner pipe wall is maintained in a wet or moistened condition at all times. Corrosion, of course, is accelerated by the normally rapid flow of gasoline. through pipe lines.

In the practice of my invention, I generally use mahogany sulfonates rather than the corresponding sulfonic-acids but the latter are applicable as previously indicated. The sulfonic acids and sulfonates may be typified by the formula RSOaX, in which It represents hydrocarbon radicals derived irom petroleum and X 2 may be hydrogen, a metal, or an amine radical having a molecular weight not exceeding 150.

I have obtained best results with the amine sulfonates and, accordingly, I prefer these over the metal. sulfonates. One advantage of the amine sulfonates, apart from their greater effectiveness in the respect of corrosion inhibition, is that they leave no residue on burning or combustion of the fuel.

The mahogany sulfonates are prepared directly or indirectly from sulfuric acid-treated oil. Ordinarily. the alkali and alkaline earth metal sul- Ionates are produced by reacting the acid oil, from mineral white oil manufacture for example, with the hydroxide of the metal or with the oxide in the presence of water. Other metal sulronates, as the cadmium and manganese sulfonates, are most expeditiously produced, metathetically, by nation of appropriate salts of the metals, e. g. CdClz, MnSOr, with the sodium sulfonate, while still others are obtained most readily byreacting a theoretical excess of the acetate of the metal with the acid oil. In some instances, notably aluminum,the sulfonate can be prepared by direct reaction of the metal and acid 011.

Ordinarily, I obtain the amine sulfonates by reacting the amine and acid oil directly, using the amine in substantially theoretically required proportions as determined by the acid number of the oil. In most cases heat is evolved. Where the solution of the product sulfonate is not clear, it may generally be rendered so by heating to a temperature of the order of 150-180 F. The amine sulfonates which settle out of the reaction mixture can usually be solubilized by dilution with an amount of kerosene equal to the volume of oil present. In some instances, the addition of a small amount of water, as 5% on the weight of the reaction mixture, and the use of temperatures upwards of 260 F. are necessary to achieve reaction between the amine and acid oil. This is required in the case of alpha naphthylamine sulfonate, for example.

In Table I below are given properties of amine sulfonate products I have prepared and tested.

Table I Percent of Theoretical Percent Theoretical Nitrogen gm; Amine Descnptmn Used Aniline sulionate 0. 39 0. 33 109' sulionate in oil; slightly hazy. Butylamine sulfonate. 0. 33 0. 33 l sulfonate in oil; light and clear. Dlethylamlne sulionate. 0.30 0. 33 115 10% sulfonate in 011; light and clear. Dimetbyl-aniline sulfonate- 0.37 0. 32 100 10% sulfonate m oil. Ethanolamino sulfonate 2. l2 9 2. 77 115 76% sullonate in o l. Ethylamine sulfonate 0, 30 0. 33 115 10% sulfonate in or]; light and clear. Ethylenediamine sulfonate 2. 7 I 6. 6 100 41% sulionate in o l. Alpha-naphthylamine sulionate 0. 37 0. 32 100 10% sulfonate n oil; dark red color. Piperidine sulfonate 4 0. 15 0.33 115 10% sulfonate in oil; light and clear. Pyridine suliouate i 0.08 i 0. 16 100 5% suliouate in oil and kerosene. Triethanolamine sulionato 0.58 i 2.36 115 24% sulionate in oil, hazy.

1 Tested as 5% concentrate in oil and k. Calculated for an oil tree sulionate. 8 Calculated for a concentrate containing 57 ml! 4 Kieldahl nitrogen determinations are not ouate. quantitative for pyridine derivatives,

acsasos Metal sulfonates I have prepared and tested include aluminum sulfongte, cadmium sulfonate, calcium suifonate, copper sulfonate, ferric sulfonate, lead sulfonate, nickel sulfonate, sodium sulfonate and zinc sulfonate.

I have found it advantageous to incorporate the sulfonate in the distillate as an oil concentrate containing about 10% of the sulfonate. Where the sulfonate is insoluble or incompletely soluble in the oil component of the acid oil from which it was derived, alcohol or benzene, for example, may be added in sufllcient amounts to bring all of it. into solution.

The suitability of the mahogany sulfonic acids and sulfonates as pipe line rust inhibitors is demonstrated by subjecting blends containing the sulfonic acids or sulfonates to a test analogous to that carrying ASTM designation D-665-42T. According to my modified test, a polished mild steel strip is suspended in a beaker fitted with a me- 20 chanical stirrer and containing 350 mls. of the test blend. The blend is stirred for 30 minutes after which 50 mls. thereof are removed and 30 mls. of distilled water substituted. Stirring'is containued for 48 hours or longer and the strip then inspected for rust.

The appended table compares the effectiveness of various additives withinthe scope of my invention in such test. In the experiments of the table kerosene was employed as the inhibited distillate because it is less volatile than gasoline.

Table II Additive Conc.,

li a/ugg i bis. 35, R t expr as us Additive amount Weight Rating 1 cone. containing Amine 10% dry soap) Blank Completely rusted. M ahogony sulionic acids. is B++ 25 B++ 25 93 3+ Do 100 93 A Butylamine suifonate 25 73 13+ Do 36 73 13+ Diethylamine sulionate... 26 73 B++ o 36 73 A Dimghyl aniline suito- 25 121 A l na Ethanolamine suii'onatci8 61 B Ethylamine sulionate...-- 25 45 B Do 36 45 B++ Ethylene diamine sulfo 25 60 B ns Alpha-naphthylamine 25 143 B++ sulio late. Piperidine sulfonste 25 85 13+ Pyri e sulfqnate 2s 79 B++ Triethanolamine mile- 12 149 13+ 36 B+ Cadmium sulionate. 30 B Do 100 3+ Calcium sulionate (basic). 25 B Cop r sulionate 18 B+ 36 A Ferric sulionatc..- 36 B 1 Do 75 A Lead sullonate.--. 36 B+ Do 100 A Sodium sulfonate 25 B+ 1 Ratings indicate the area of the surface covered by rust.

A=No rust on strip. B++=Trace of rust on strip. B+-Less than of surface rusted. 13-5-25 0! surface rusted.

1 Test period, 72 11%;!-

As indicated hereinbefore, the sulfonates of amines having molecular weights in excess of 150 are, for some unexplicable reason, relatively ineffective in the test. Thus, when the sulfonates of dicyclohexylamine and laurylamine, having molecular weights of 181 and 185, respectively, were subjected to the test almost of the surface of the strip was found to be rusted in each case, even with additive concentrations of lbs. of 10% concentrate for each 1,000 bbls. of

corporating in gasoline charged to the pipe line from 1 to 100 parts per million of a material from the group consisting of petroleum mahogany sulfonic acids and petroleum mahogany sulfonates.

3. Method of retarding internal corrosion'of pipe lines containing iron which comprises incorporating in kerosene charged to the pipe line from 1 to 100 parts per million of a material from the group consisting of petroleum mahogany sulfonic acids and petroleum mahogany sulfonates.

4. Method of retarding internal corrosion of pipe lines containing iron which comprises incorporating in fuel oil charged to the pipe line from 1 to 100 parts per million of a material from the group consisting of petroleum mahogany sulfonic acids and petroleum mahogany sulfonates.

FRANKLIN M. WATKINS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,630,101 Wilkin May 24, 1927 2,125,305 Murphy Aug. 2, 1938 2,141,848 Adams Dec. 27, 1938 2,333,206 Sloan Nov. 2, 1943 2,412,634 Schwartz Dec. 17, 1946 2,413,311 Cohen Dec. 31, 1946 2,449,025 Turner Sept. 7, 1948 2,453,690 Bray Nov. 16, 1948 

1. METHOD RETARDING INTERNAL CORROSION OF PIPE LINES CONTAINING IRON WHICH COMPRISES INCORPORATING IN THE LIGHT PETROLEUM DISTILLATE CHARGED TO THE PIPE LINE FROM 1 TO 100 PARTS PER MILLION OF A MATERIAL FROM THE GROUP CONSISTING OF PETROLEUM MAHOGANY SUFONIC ACIDS AND PETROLEUM MAHOGANY SULFONATES. 